Answer:
Two-variable inequalities from their graphs (video)
Step-by-step explanation:
Franny: 2.849 tons is the answer
(a) See the attached sketch. Each shell will have a radius <em>y</em> chosen from the interval [2, 4], a height of <em>x</em> = 2/<em>y</em>, and thickness ∆<em>y</em>. For infinitely many shells, we have ∆<em>y</em> converging to 0, and each super-thin shell contributes an infinitesimal volume of
2<em>π</em> (radius)² (height) = 4<em>πy</em>
Then the volume of the solid is obtained by integrating over [2, 4]:

(b) See the other attached sketch. (The text is a bit cluttered, but hopefully you'll understand what is drawn.) Each shell has a radius 9 - <em>x</em> (this is the distance between a given <em>x</em> value in the orange shaded region to the axis of revolution) and a height of 8 - <em>x</em> ³ (and this is the distance between the line <em>y</em> = 8 and the curve <em>y</em> = <em>x</em> ³). Then each shell has a volume of
2<em>π</em> (9 - <em>x</em>)² (8 - <em>x</em> ³) = 2<em>π</em> (648 - 144<em>x</em> + 8<em>x</em> ² - 81<em>x</em> ³ + 18<em>x</em> ⁴ - <em>x</em> ⁵)
so that the overall volume of the solid would be

I leave the details of integrating to you.
4 will be the correct answer to your question
1. Using "exact" interest, your charge will be
.. I = Prt
.. I = $855.28*0.154*(31/365)
.. I = $11.19
2. It will take 52.01 months to pay off the loan.
3. Your payment on 15,250 for 4 years will be $363.41. The effective interest rate that payment represents on a loan of $15,000 is 7.604%
4. Todd's monthly payments will be $409.06, so his total outlay will be
.. tax+license + down payment + loan repayment
.. = 1200 +1000 +48*409.06
.. ≈ $21,835